U.S. patent application number 16/314603 was filed with the patent office on 2020-12-10 for multifunctional true triaxial rock drilling test system and method.
This patent application is currently assigned to SHANDONG UNIVERSITY. The applicant listed for this patent is SHANDONG TIANQIN ENGINEERING TECHNOLOGY CO., LTD., SHANDONG UNIVERSITY. Invention is credited to Hongke GAO, Bei Jiang, Shucai LI, Qi WANG.
Application Number | 20200386659 16/314603 |
Document ID | / |
Family ID | 1000005076182 |
Filed Date | 2020-12-10 |
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United States Patent
Application |
20200386659 |
Kind Code |
A1 |
LI; Shucai ; et al. |
December 10, 2020 |
MULTIFUNCTIONAL TRUE TRIAXIAL ROCK DRILLING TEST SYSTEM AND
METHOD
Abstract
A multifunctional true triaxial rock drilling test system and
method; rock cores are respectively taken from a plurality of
drilling holes on the same test piece, uniaxial test and triaxial
test are respectively performed on these rock cores to obtain
multiple groups of mechanical property parameters, multiple groups
of drilling parameters are obtained according to a multifunctional
true triaxial rock drilling tester that can directly measure the
drilling parameters, relational expression between mechanical
property parameters of rock mass and the drilling parameters is
established, and mechanical property parameters of rock mass can be
obtained just by detecting the drilling parameters of the rock mass
through the relational expression. The multifunctional true
triaxial rock drilling tester is preset test device, has function
of performing triaxial loading on the test piece, and can simulate
drilling process of drilling rig in a three-way confining pressure
state in underground engineering of the test piece.
Inventors: |
LI; Shucai; (Jinan, CN)
; WANG; Qi; (Jinan, CN) ; Jiang; Bei;
(Jinan, CN) ; GAO; Hongke; (Jinan, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHANDONG UNIVERSITY
SHANDONG TIANQIN ENGINEERING TECHNOLOGY CO., LTD. |
Jinan, Shandong
Heze, Shandong |
|
CN
CN |
|
|
Assignee: |
SHANDONG UNIVERSITY
Jinan, Shandong
CN
SHANDONG TIANQIN ENGINEERING TECHNOLOGY CO., LTD.
Heze, Shandong
CN
|
Family ID: |
1000005076182 |
Appl. No.: |
16/314603 |
Filed: |
January 7, 2017 |
PCT Filed: |
January 7, 2017 |
PCT NO: |
PCT/CN2017/070553 |
371 Date: |
April 4, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 3/18 20130101; G01N
33/24 20130101; G01N 3/10 20130101; E21B 49/02 20130101; E21B 44/04
20130101; E21B 49/003 20130101; G01N 2203/0048 20130101; G01N
2203/0019 20130101 |
International
Class: |
G01N 3/10 20060101
G01N003/10; G01N 3/18 20060101 G01N003/18; G01N 33/24 20060101
G01N033/24; E21B 44/04 20060101 E21B044/04; E21B 49/00 20060101
E21B049/00; E21B 49/02 20060101 E21B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 6, 2016 |
CN |
201610529362.9 |
Jul 6, 2016 |
CN |
201610529764.9 |
Claims
1. A multifunctional true triaxial rock drilling test system,
comprising a pressure loading device, a drilling rig unit, a
monitoring control unit and a hydraulic station, wherein the
hydraulic station provides power for the pressure loading device,
and the pressure loading device applies a confining pressure to a
rock test piece placed therein; the drilling rig unit is arranged
at an upper end of the pressure loading device for drilling the
rock test piece under pressure; the monitoring control unit
controls the pressure loading device to apply the pressure, and
meanwhile controls either of two groups of values of the drilling
rig, namely a torque and a rotating speed, and a drilling pressure
and a displacement.
2. The multifunctional true triaxial rock drilling test system
according to claim 1, wherein the pressure loading device comprises
a pressure chamber, and a confining pressure loading device is
arranged on the outer side of the pressure chamber to apply the
confining pressure to the rock test piece, and a test piece
platform for carrying the pressure chamber and the rock test piece
is arranged at the lower end of the pressure chamber.
3. The multifunctional true triaxial rock drilling test system
according to claim 2, wherein the confining pressure loading device
comprises two groups of vertically arranged lateral loading plates,
each group of lateral loading plates comprises two opposite lateral
loading plates arranged in parallel, and the two groups of lateral
loading plates form a rectangular loading structure to surround the
test piece in the pressure chamber, the confining pressure loading
device further comprises a lateral hydraulic oil cylinder, the
hydraulic oil cylinder drives a piston rod to push the lateral
loading plate to apply a horizontal pressure to the test piece, and
a lateral reaction force plate is arranged on the outer side of the
lateral hydraulic oil cylinder.
4. The multifunctional true triaxial rock drilling test system
according to claim 1, wherein the drilling rig unit comprises a
drilling rig embedded in a drilling rig slide rail, the drilling
rig axially moves up and down along the drilling rig slide rail,
and the drilling rig slide rail is fixed on the reaction force
frame at the top of the test piece through a drilling rig slide
rail fixing plate.
5. The multifunctional true triaxial rock drilling test system
according to claim 4, wherein the drilling rig unit further
comprises a servo motor, a speed reduction mechanism and a belt
transmission device, the belt transmission device and the speed
reduction mechanism constitute a two-stage speed reduction
mechanism, the speed reduction multiples are changed with the
diameter ratio of gears at both ends of a belt in the belt
transmission device, the upper part of the drilling rig is fixedly
connected to the drilling rig top hydraulic oil cylinder, the
drilling rig top hydraulic oil cylinder provides an axial force for
the drilling rig, and the drilling rig servo motor provides a
rotating force for the drilling rig.
6. The multifunctional true triaxial rock drilling test system
according to claim 1, wherein the monitoring control unit comprises
a monitoring unit, and specifically comprises lateral confining
pressure sensors for detecting lateral confining pressure of on
four directions, a lateral displacement sensor for detecting a
moving distance of the lateral loading plate, and a drilling rig
torque sensor for detecting the torque of the drilling rig, a
drilling rig rotating speed sensor for detecting the rotating speed
of the drilling rig, a drilling rig pressure sensor for detecting
pressure applied by the drilling rig downward, and a drilling rig
displacement sensor for detecting the vertical moving distance of
the drilling rig; and the servo motor has a rotating speed
sensor.
7. The multifunctional true triaxial rock drilling test system
according to claim 6, further comprising an axial pressure loading
device for applying an axial pressure to the rock test piece,
wherein the axial pressure loading device comprises an axial
hydraulic oil cylinder, an axial loading plate is arranged at the
lower part of the test piece, and the axial hydraulic oil cylinder
pushes the axial loading plate to drive the rock test piece to
perform axial movement and contacts the reaction force frame to
apply an axial force to the rock test piece.
8. The multifunctional true triaxial rock drilling test system
according to claim 7, further comprising an axial pressure sensor
arranged at the axial hydraulic oil cylinder, wherein the lateral
confining pressure sensor is arranged on an oil supply pipeline,
and the lateral displacement sensor is arranged on the side of the
lateral hydraulic oil cylinder.
9. The multifunctional true triaxial rock drilling test system
according to claim 8, wherein the monitoring control unit comprises
a control unit, specifically comprising a logic controller, a power
amplifier and a servo motor, the logic controller receives signals
of the sensors, compares the signals with a set value, sends a
voltage instruction to control the drilling rig servo motor and the
hydraulic station servo motor to work, and achieves closed-loop
control, and the hydraulic station servo motor is connected with
the axial hydraulic oil cylinder and the lateral hydraulic oil
cylinder respectively.
10. The multifunctional true triaxial rock drilling test system
according to claim 9, wherein the control unit controls the
drilling rig in four modes: A. controlling a torque and a drilling
rate, and collecting a drilling pressure and a rotating speed; B.
controlling the torque and the drilling pressure, and collecting a
rotating speed and a drilling rate; C. controlling the rotating
speed and the drilling rate, and collecting the torque and the
drilling pressure; D. controlling the rotating speed and the
drilling pressure, and collecting the torque and the drilling rate;
the control unit controls the hydraulic station servo motor to
control the axial pressure and the confining pressure of the test
piece in three control modes: A. a constant strain loading mode, in
which small strains occurring in the test piece within a unit time
are the same; B. a constant pressure incremental loading mode, in
which the pressure increase of the hydraulic oil cylinder within
the unit time is the same; C. a constant force maintenance mode, in
which the test piece is kept at a set confining pressure value.
11. The multifunctional true triaxial rock drilling test system
according to claim 10, wherein the control method of constant
strain loading of the test piece is as follows: the axial loading
device pushes the pressure chamber to ascend, so that the top of a
uniaxial test piece contacts a platform plate below the reaction
force frame, the uniaxial test piece is in a uniaxial compression
state, the axial loading device is controlled to be in a constant
strain loading mode, and the axial pressure is applied to the test
piece at a loading speed suggested by the International Society for
Rock Mechanics until the test piece is broken.
12. The multifunctional true triaxial rock drilling test system
according to claim 10, wherein the control method of constant
pressure incremental loading of the test piece is as follows: three
main stresses are independently applied to the rock mass test
piece, the constant pressure incremental loading is that the same
pressure is applied to a certain side face of the test piece within
the unit time; and the working method is that the logic controller
records the current pressure read by the lateral pressure sensor or
the axial pressure sensor, and controls the servo motor to drive
the oil cylinder to pressurize the test piece, the logic controller
records the pressure change of the pressure sensor, and when the
pressure reaches the preset increment within the unit time, the
logic controller controls the servo motor to stop and repeats the
above work within the next unit time.
13. A test method for characterizing rock mass characteristics by
using drilling parameters in underground engineering, wherein rock
cores are respectively taken from a plurality of drilling holes on
the same test piece, a uniaxial test and a triaxial test are
respectively performed on these rock cores to obtain multiple
groups of mechanical property parameters, multiple groups of
drilling parameters are obtained by the multifunctional true
triaxial rock drilling test system according to claim 1, a
relational expression between mechanical property parameters of
rock mass and the drilling parameters is established, and the
mechanical property parameters of rock mass can be obtained just by
detecting the drilling parameters of the rock mass through the
relational expression.
14. A test method for characterizing rock mass characteristics by
using drilling parameters in underground engineering, wherein rock
cores are respectively taken from a plurality of drilling holes on
the same test piece, a rock mass integrity parameter RQD value of
the rock core is measured, multiple groups of drilling parameters
are obtained according to the multifunctional true triaxial rock
drilling test system according to claim 1, a relational expression
between mechanical property parameters of rock mass and the
drilling parameters is established, and the integrity parameter RQD
value of rock mass can be obtained just by detecting the drilling
parameters of the rock mass through the relational expression.
15. The test method for characterizing rock mass characteristics by
using drilling parameters in underground engineering according to
claim 13, wherein the rock core is divided into multiple segments
from top to bottom, and the mechanical property parameters of the
segments are obtained respectively.
16. The test method for characterizing rock mass characteristics by
using drilling parameters in underground engineering according to
claim 13, comprising the specific steps as follows: Step 1)
according to the test purpose, determining rock mass basic factors
affecting the three-way confining pressure loading drilling, and
designing a reasonable test solution; step 2) preparing the
corresponding test piece according to the test solution; step 3)
performing a three-way confining pressure drilling test on the
prepared test piece, collecting the drilling parameters in a
drilling process of the test piece in the test, and collecting the
rock core of the test piece; step 4a) performing statistics on the
core collection rate of the rock core of the test piece, and
measuring the integrity parameter RQD value of the test piece; step
4b) cutting and grinding the rock core obtained from the test
piece, manufacturing a plurality of standard test pieces, and
performing a triaxial test and a uniaxial test to measure the
mechanical property parameters of the test piece material; step 5)
preprocessing the collected data, and then establishing the
relationship between the processed data and the same-depth rock
mechanical properties and rock mass integrity parameters, including
an optimal regression relational expression of the uniaxial
compressive strength and the drilling parameters, the optimal
regression relational expression of a cohesive force and the
drilling parameters, the optimal regression relational expression
of an inner friction angle and the drilling parameters, the optimal
regression relational expression of modulus of elasticity and the
drilling parameters, a rock mass integrity parameter RQD value, a
torque fracture index QD.sub.m and a rotating speed fracture index
QD.sub.r.
17. The test method for characterizing rock mass characteristics by
using drilling parameters in underground engineering according to
claim 13, wherein the relationship between the rock mass integrity
parameter RQD value and the drilling parameters is established; on
the basis of a large number of test data, formula fitting is
performed on the RQD value of the test piece, the torque fracture
index QD.sub.m and the rotating speed fracture index QD.sub.r by
using a multiple linear regression method; and the final form of
the fitting formula is:
RQD=.beta..sub.0+.beta..sub.1QD.sub.m+.beta..sub.2QD.sub.r wherein
.beta..sub.0, .sym..sub.1 and .beta..sub.2 all represent regression
coefficients.
18. The test method for characterizing rock mass characteristics by
using drilling parameters in underground engineering according to
claim 17, wherein the torque fracture index QD.sub.m and a rotating
speed fracture index QD.sub.r are calculated by using the following
formulas: Q D m = .SIGMA.h i 1 + .SIGMA. l j 1 H Q D r = .SIGMA.h i
2 + .SIGMA. l j 2 H ##EQU00016## in which h.sub.i.sup.1 represents
the length of the ith segment of which the torque significant rate
m is less than the critical value in a certain drilling hole,
l.sub.i.sup.1 represents the length of the jth segment of which the
torque significant rate index is greater than the critical value
and the length is less than 100 mm, h.sub.i.sup.2 represents the
length of the ith segment of which the rotating speed significant
rate m is greater than the critical value in a certain drilling
hole, l.sub.i.sup.2 represents the length of the jth segment of
which the rotating speed significant rate index is greater than the
critical value and the length is less than 100 mm, and H represents
the total length of a certain drilling hole.
19. A method for evaluating an anchoring and grouting reinforcement
effect based on drilling parameters, comprising: based on the
multifunctional true triaxial rock drilling test system according
to claim 1, performing an indoor drilling test on the rock test
piece obtained onsite before and after anchoring and grouting
reinforcement, designing an anchoring and grouting reinforcement
solution according to the representative value of the equivalent
uniaxial compressive strength of the test piece before the
anchoring and grouting reinforcement, and judging the
reasonableness of the anchoring and grouting reinforcement solution
via a guarantee rate .lamda. of the equivalent uniaxial compressive
strength after the test piece is reinforced.
20. The method for evaluating the anchoring and grouting
reinforcement effect based on drilling parameters according to
claim 19, comprising the following specific steps: Step A): taking
onsite fractured rocks in an underground engineering, manufacturing
indoor drilling test pieces, and dividing the indoor drilling test
pieces into several groups; step B): taking any group as an
example, randomly taking a part of test pieces, implementing an
indoor drilling test, recording the drilling parameters of three
test pieces, substituting the drilling parameters of each test
piece into the optimal regression relational expression of the
uniaxial compressive strength and the drilling parameters of
preprocessing the collected data, and then establishing the
relationship between the processed data and the same-depth rock
mechanical properties and rock mass integrity parameters, including
an optimal regression relational expression of the uniaxial
compressive strength and the drilling parameters, the optimal
regression relational expression of a cohesive force and the
drilling parameters, the optimal regression relational expression
of an inner friction angle and the drilling parameters, the optimal
regression relational expression of modulus of elasticity and the
drilling parameters, a rock mass integrity parameter ROD value, a
torque fracture index QD.sub.m and a rotating speed fracture index
QD.sub.r to obtain the equivalent uniaxial compressive strength of
each test piece, and then obtaining a representative value of the
equivalent uniaxial compressive strength of the group of fractured
rock masses; step C): comparing the representative value of the
equivalent uniaxial compressive strength obtained in the step B)
with an expected strength value, designing an anchoring and
grouting solution, implementing the same anchoring and grouting
reinforcement solution on the rest test pieces in the group, and
curing the test pieces under the same conditions; step D):
performing the indoor drilling test on the cured reinforced test
piece, and substituting the drilling parameters into the optimal
regression relational expression of the uniaxial compressive
strength and the drilling parameters of preprocessing the collected
data, and then establishing the relationship between the processed
data and the same-depth rock mechanical properties and rock mass
integrity parameters, including an optimal regression relational
expression of the uniaxial compressive strength and the drilling
parameters, the optimal regression relational expression of a
cohesive force and the drilling parameters, the optimal regression
relational expression of an inner friction angle and the drilling
parameters, the optimal regression relational expression of modulus
of elasticity and the drilling parameters, a rock mass integrity
parameter ROD value, a torque fracture index QD.sub.m and a
rotating speed fracture index QD.sub.r to obtain the equivalent
uniaxial compressive strength of each test piece; step E):
calculating a guarantee rate of the equivalent uniaxial compressive
strength after the reinforcement of the group of test pieces, if
the guarantee rate is greater than 95%, judging that the anchoring
and grouting reinforcement solution is reasonable, or otherwise,
judging that the anchoring and grouting reinforcement solution is
unreasonable.
21. The method for evaluating the anchoring and grouting
reinforcement effect based on drilling parameters according to
claim 20, wherein the calculation method of the equivalent
compressive strength of the test piece in the step C) comprises:
substituting the drilling parameters, including the torque m, the
rotating speed r, the drilling pressure n, drilling speed v and the
drilling specific work w of the drilling rig into the optimal
regression relational expression of the uniaxial compressive
strength and the drilling parameters preprocessing the collected
data, and then establishing the relationship between the processed
data and the same-depth rock mechanical properties and rock mass
integrity parameters, including an optimal regression relational
expression of the uniaxial compressive strength and the drilling
parameters, the optimal regression relational expression of a
cohesive force and the drilling parameters, the optimal regression
relational expression of an inner friction angle and the drilling
parameters, the optimal regression relational expression of modulus
of elasticity and the drilling parameters, a rock mass integrity
parameter ROD value, a torque fracture index QD.sub.m and a
rotating speed fracture index QD.sub.r to obtain the equivalent
uniaxial compressive strength of each test piece.
22. The method for evaluating the anchoring and grouting
reinforcement effect based on drilling parameters according to
claim 20, wherein the representative value of the equivalent
uniaxial compressive strength of the fractured rock mass is
represented by the average value of the equivalent compressive
strength of part of test pieces; if the deviation between the
maximum value and the average value or between the minimum value
and the average value is greater than 15%, an intermediate value is
used as the representative value, and if the deviations between the
maximum value and the average value and between the minimum value
and the average value are both greater than 15%, the group of data
is invalid.
23. The method for evaluating the anchoring and grouting
reinforcement effect based on drilling parameters according to
claim 20, wherein the anchoring and grouting reinforcement solution
is to determine a slurry-water-cement ratio, a grouting pressure,
an anchor rod length and an anchor rod diameter.
24. The method for evaluating the anchoring and grouting
reinforcement effect based on drilling parameters according to
claim 20, wherein the calculation method of the guarantee rate of
the equivalent uniaxial compressive strength is: .lamda. = num N
.times. 100 % ##EQU00017## in which num represents the number of
reinforced test pieces with equivalent uniaxial compressive
strength greater than the expected strength value in the group, and
N represents the total number of the reinforced test pieces in the
group.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the technical field of
geotechnical engineering investigation, in particular to a
multifunctional true triaxial rock drilling test system and
method.
BACKGROUND OF THE INVENTION
[0002] It is relatively frontier at present that a relevance
research is made by using drilling parameters (torque, rotating
speed, drilling pressure, drilling rate, drilling specific work),
rock mechanics parameters (uniaxial compressive strength, Poisson's
ratio, internal friction angle, modulus of elasticity), and rock
mass characteristics (fracture width, quantity and rock mass
integrity coefficient) in a drilling process of a drilling rig. The
method has the advantages of being visual, efficient and able to
perform onsite real-time judgment because no rock core is collected
in the drilling process, and the rock mass mechanical parameters
are directly characterized by using the drilling parameters of the
drilling rig. At present, few indoor test devices for the research
are available and have the following defects:
[0003] (1) A device for applying a confining pressure and an axial
pressure is not employed, and the rock at an underground
engineering site is generally in a three-way pressure state, which
results in a larger difference between drilling conditions of the
existing test device and conditions at the engineering site.
[0004] (2) Thermodynamic coupling conditions cannot be applied to a
rock mass test piece, the influence of thermal coupling of the rock
mass on the drilling parameters of the drilling rig cannot be
researched, and the mechanical properties of the rock mass under
the action of the thermal coupling cannot be researched.
[0005] The traditional common methods for evaluating the
reinforcement effect after surrounding rock anchoring and grouting
include a transient electromagnetic method, a geological radar
method and a drilling method, but these methods have the following
problems:
[0006] (1) due to the complexity of the geological conditions at
the construction site, it is often difficult to obtain accurate
results by using the transient electromagnetic method and the
geological radar method, and the transient electromagnetic method
and the geological radar method can only be used for performing
qualitative analysis and judgment on the reinforced weak
surrounding rock via images, but cannot be used for realizing
accurate quantitative analysis of the reinforcement effect.
[0007] (2) In the application of the drilling method, the time
interval from onsite core collection to experimental report
acquisition is long, which seriously restricts the construction
progress and increases the engineering budget cost.
[0008] (3) During drilling in weak and fractured stratum, a rock
core collection rate and the integrity are difficult to be ensured,
so that the physical properties and mechanical parameters of the
local rock formation cannot be obtained, and as a result, the
changes of the mechanical parameters of the rock before and after
grouting cannot be quantitatively compared.
[0009] At present, neither an experimental device for drilling
parameter test and drilling process research under three-way
confining pressure conditions, nor a method for evaluating an
anchoring and grouting effect of a monitoring device based on
drilling parameter is disclosed.
SUMMARY OF THE INVENTION
[0010] The objective of the present invention is to provide a
multifunctional true triaxial rock drilling test system, which can
complete drilling of a drilling rig under multi-directional
confining pressure conditions, and an operation parameter
measurement test of the drilling rig in a drilling process.
[0011] A second objective of the present invention is to provide a
control method of the multifunctional true triaxial rock drilling
test system. The system can be effectively controlled according to
the method to obtain accurate measurement data.
[0012] A test method for characterizing rock mass characteristics
by using drilling parameters in underground engineering is also
provided. In the test method, the rock mass characteristics are
characterized by using drilling parameters (drilling rate, torque,
rotating speed, drilling pressure, drilling specific work), the
relationship between the drilling parameters and the mechanical
parameters (uniaxial compressive strength, cohesive force, internal
friction angle, modulus of elasticity) of rock mass, and rock mass
integrity parameters RQD can be established, it is convenient to
detect the performance of the rock mass, and the time for
performing a triaxial test and a uniaxial test on the rock core can
be saved.
[0013] A fourth objective of the present invention is to provide a
method for evaluating an anchoring and grouting reinforcement
effect based on drilling parameters. The method provides a test use
of the true triaxial rock drilling test system of the present
invention, represents one of the functions of the test system,
gives the evaluation method of the anchoring and grouting
reinforcement effect and has important application
significance.
[0014] In order to achieve the above objectives, the present
invention adopts the following technical solutions:
[0015] The first solution provided by the present invention is as
follows: a multifunctional true triaxial rock drilling test system
includes a pressure loading device, a drilling rig unit, a
monitoring control unit and a hydraulic station, wherein the
hydraulic station provides power for the pressure loading device,
and the pressure loading device applies a confining pressure to a
rock test piece placed therein;
[0016] the drilling rig unit is arranged at an upper end of the
pressure loading device for drilling the rock test piece under the
application of the three-way confining pressure;
[0017] the monitoring control unit controls the pressure loading
device to apply the pressure, and also controls either of two
groups values of the drilling rig, namely a torque and a rotating
speed, and a drilling pressure and displacement.
[0018] The test piece may have any size ranging from 100
mm.times.100 mm.times.150 mm to 300 mm.times.300 mm.times.600 mm,
and by changing loading plates of different sizes and placing steel
cushion blocks of different sizes at the upper side and the lower
side of the test piece, a loading rod acts on the center of the
side face of the test piece to apply confining pressures to the
cushion blocks of different sizes.
[0019] The pressure loading device includes a pressure chamber, and
a confining pressure loading device is arranged on the outer side
of the pressure chamber to apply the confining pressure to the rock
test piece.
[0020] A platform plate is fixedly connected below a reaction force
frame, the platform plate is directly in contact with the rock test
piece, and reserved holes are formed in the middle of the platform
plates and the reaction force frame to allow passage of a drill
pipe of the drilling rig.
[0021] A test piece platform for carrying the pressure chamber and
the rock test piece is arranged at the lower end of the pressure
chamber.
[0022] Further, the confining pressure loading device includes two
groups of vertically arranged lateral loading plates, each group of
lateral loading plates includes two opposite lateral loading plates
arranged in parallel, and the two groups of lateral loading plates
form a rectangular loading structure to surround the test piece in
the pressure chamber.
[0023] The application pressures of the two groups of lateral
loading plates are different or the same, so that the confining
pressure application of the test piece under various confining
pressure conditions can be realized.
[0024] The confining pressure loading device further includes a
lateral hydraulic oil cylinder, the hydraulic oil cylinder drives a
piston rod to push the lateral loading plate to apply a horizontal
pressure to the test piece, and the end part of the lateral
hydraulic oil cylinder is embedded in a lateral reaction force
plate for providing a supporting reaction force for the lateral
hydraulic oil cylinder.
[0025] The drilling rig unit includes a drilling rig embedded in a
drilling rig slide rail, the drilling rig axially moves up and down
along the drilling rig slide rail, the drilling rig slide rail is
fixed on the reaction force frame at the top of the test piece
through a drilling rig slide rail fixing plate, the drilling rig is
fixedly connected with a drilling rig servo motor and moves
downward or upward under the push or pull of a drilling rig top
hydraulic oil cylinder at the upper part.
[0026] The drilling rig servo motor provides a rotating force for
the drilling rig, and the drilling rig top hydraulic oil cylinder
provides a downward pressure for the drilling rig, and the drill
pipe of a drilling bit of the drilling rig is in contact with the
test piece via the reserved holes in the reaction force frame and
the loading plate at the top of the test piece to generate a
drilling function.
[0027] The drilling rig unit further includes a servo motor, a
speed reduction mechanism and a belt transmission device, the belt
transmission device and the speed reduction mechanism constitute a
two-stage speed reduction mechanism, the speed reduction multiples
are changed with the diameter ratio of gears at both ends of a belt
in the belt transmission device, the upper part of the drilling rig
is fixedly connected to the drilling rig top hydraulic oil cylinder
which provides an axial force for the drilling rig, and the
drilling rig servo motor provides a rotating force for the drilling
rig.
[0028] The monitoring control unit includes a monitoring unit, and
specifically includes a lateral confining pressure sensor for
detecting lateral confining pressures of upper sides on four
directions, a lateral displacement sensor for detecting a moving
distance of the lateral loading plate, and a drilling rig torque
sensor for detecting the torque of the drilling rig, a drilling rig
rotating speed sensor for detecting the rotating speed of the
drilling rig, a drilling rig pressure sensor for detecting a
pressure applied by the drilling rig downward, and a drilling rig
displacement sensor for detecting the vertical moving distance of
the drilling rig; and the monitoring control unit further includes
an axial pressure sensor arranged at an axial hydraulic oil
cylinder, the lateral confining pressure sensor is arranged on an
oil supply pipeline, the lateral displacement sensor is arranged on
the side of the lateral hydraulic oil cylinder, and the servo motor
has a rotating speed sensor.
[0029] In a preferred solution, four pressure sensors, four
displacement sensors and one torque sensor are contained in total,
the servo motor has the rotating speed sensor, the torque sensor is
connected with the drill pipe at one end and is connected with a
main shaft of the drilling rig at the other end, and the pressure
and displacement sensors respectively monitor the pressure and the
displacement of the drilling rig top hydraulic oil cylinder at the
upper part of the drilling rig, an axial loading device and a
two-direction confining pressure loading device, the pressure
sensors are installed on the oil supply pipelines of the four oil
cylinders, and the displacement sensors are fixed on the side faces
of the oil cylinders to measure the position changes of the oil
cylinders and the corresponding loading plates.
[0030] The monitoring control unit includes a control unit,
specifically including a logic controller, a power amplifier and a
servo motor, the logic controller receives signals of the pressure
sensor, the displacement sensor and the torque sensor, compares the
signals with a set value, sends a voltage instruction to control
the drilling rig servo motor and a hydraulic station servo motor to
work, and achieves closed-loop control, and the hydraulic station
servo motor is connected with the axial hydraulic oil cylinder and
the lateral hydraulic oil cylinder respectively.
[0031] A control method of the above multifunctional true triaxial
rock drilling test system is provided, wherein the control unit
controls the drilling rig in four modes:
[0032] A. controlling a torque and a drilling rate, and collecting
a drilling pressure and a rotating speed;
[0033] B. controlling the torque and the drilling pressure, and
collecting a rotating speed and a drilling rate;
[0034] C. controlling the rotating speed and the drilling rate, and
collecting the torque and the drilling pressure;
[0035] D. controlling the rotating speed and the drilling pressure,
and collecting the torque and the drilling rate.
[0036] By controlling two parameters and measuring the other two
parameters, the parameter change can be manually controlled, an
intuitive research is made on the influence of the changes of the
controlled variables on the other drilling parameters and the
response sensitivity to the rock mechanical parameters, and the
following situations are avoided: the parameters in the drilling
process of an ordinary drilling rig are unstable and the operation
mode is single, such that it is difficult to study the relationship
between the drilling parameters and the rock mechanical parameters.
The control unit controls the hydraulic station servo motor to
control the axial pressure and the confining pressure of the test
piece in three control modes:
[0037] A. a constant strain loading mode, in which small strains
occurring in the test piece within a unit time are the same;
[0038] B. a constant pressure incremental loading mode, in which
the pressure increase of the hydraulic oil cylinder within the unit
time is the same;
[0039] C. a constant force maintenance mode, in which the test
piece is kept at a set confining pressure value.
[0040] The control method of constant strain loading of the test
piece: the top of a uniaxial test piece contacts a platform plate
below the reaction force frame, the uniaxial test piece is in the
uniaxial compression state, the axial loading device is controlled
to be in a constant strain loading mode, and the axial pressure is
applied to the test piece at a loading speed suggested by the
International Society for Rock Mechanics until the test piece is
broken.
[0041] The control method of constant pressure incremental loading
of the test piece: three main stresses of the rock mass test piece
are independently applied, the constant pressure incremental
loading is that the same pressure is applied to a certain side face
of the test piece within the unit time. The working method is that
the logic controller records the current pressure read by the
lateral pressure sensor or the axial pressure sensor, and controls
the servo motor to drive the oil cylinder to pressurize the test
piece, the logic controller records the pressure change of the
pressure sensor, and when the pressure reaches the preset increment
within the unit time, the logic controller controls the servo motor
to stop and repeats the above work within the next unit time.
[0042] In addition, the test system further includes an axial
pressure loading device for applying the axial pressure to the rock
test piece, the axial pressure loading device includes an axial
hydraulic oil cylinder, an axial loading plate is arranged at the
lower part of the test piece, and the axial hydraulic oil cylinder
pushes the axial loading plate to drive the rock test piece to
perform axial movement and contacts the reaction force frame to
apply an axial force to the rock test piece.
[0043] The test piece platform is a platform for placing the test
piece in the pressure chamber, and a positioning ball is arranged
at the center of the platform for centering the test piece.
[0044] A steel heating plate is arranged at the outside of the
pressure chamber, a curved heating pipeline is arranged in the
heating plate, a pipeline inlet is welded on the upper end of one
side face of the heating plate, a pipeline outlet is welded on the
lower end of an opposite side face, so that water vapor or high
temperature liquid passes through the pipeline to heat the test
piece, and then the mechanical properties of the test piece under
thermal coupling are studied.
[0045] In the case that the test piece contains water therein or is
filled with fracture water, a sealing rubber box may be arranged at
the bottom of the test piece platform, and a rubber cover slightly
larger than the sealing rubber box may be arranged at the top of
the test piece, a pore is reserved in the middle of the rubber
cover, the axial and lateral loading plates apply the pressure to
the rubber box and the rubber cover, and a three-way pressure is
applied to the test piece through the rubber box and the rubber
cover. This design can prevent the internal water from flowing
outside, so that the test system can test the water-containing rock
mass.
[0046] The drilling rig is a rotary cutting drilling rig or an
impact drilling rig. The drilling bit of the rotary cutting
drilling rig can be set as a core collection drilling bit or a
non-core collection drilling bit.
[0047] The present invention has the function of a uniaxial testing
machine. The uniaxial test piece is placed in the pressure chamber,
the steel cushion blocks are placed at the upper side and the lower
side of the uniaxial test piece, the axial loading device lifts the
pressure chamber, so that the steel cushion blocks on the uniaxial
test piece are in contact with the platform plate below the
reaction force frame, so that the uniaxial test piece is in the
uniaxial compression state, the axial loading device is controlled
to be in a constant strain loading mode, and the axial pressure is
applied to the test piece at the loading speed suggested by the
International Society for Rock Mechanics until the test piece is
broken.
[0048] The multifunctional true triaxial rock drilling test system
can perform constant pressure incremental loading by using the
axial pressure loading device and the confining pressure loading
device, realize the independent application of the three main
stresses of the rock test piece, and has a part of functions of a
rock true triaxial testing machine.
[0049] The second solution provided by the present invention is as
follows: a test method for characterizing rock mass characteristics
by using drilling parameters in underground engineering. A drilling
test is made by the multifunctional true triaxial rock drilling
test system to obtain the drilling parameters of the test piece,
and then multiple groups of rock cores are collected from the
periphery of a drilling hole in the drilling test of the test
piece. The rock core processing methods are different depending on
different test objectives.
[0050] (1) A rock mass integrity parameter RQD value of the rock
core is measured, and a relational expression between the rock mass
RQD value and the drilling parameters is established;
[0051] (2) a uniaxial test and a triaxial test are carried out on
these cores respectively to obtain mechanical property parameters
of the test piece, and the relational expression between the
mechanical property parameters of the rock mass and the drilling
parameters is established.
[0052] Through the above relational expression, the integrity
parameter RQD value and the mechanical property parameters of the
rock mass can be obtained by simply detecting the drilling
parameters of the rock mass. Of course, the curve of the relational
expression is better to be stored in the monitoring control system
of the true triaxial rock drilling tester, and the integrity
parameters and mechanical properties of the rock mass can be
obtained in real time according to the relational expression, which
is simple and convenient.
[0053] Further, in order to measure the mechanical property
parameters of the rock core test piece, the rock core is divided
into a plurality of sections from top to bottom with a height of
100 mm, that is, the rock core is cut, polished and made into a
rock standard test piece, and the mechanical property parameters of
the sections are obtained respectively.
[0054] Further, when the relational expression between the rock
mass integrity parameter RQD value and the drilling parameters is
established, the test piece used is a fractured rock mass test
piece.
[0055] Further, in order to achieve the objective of the present
invention, the following specific steps are used:
[0056] Step 1) according to the test purpose, determining rock mass
basic factors affecting the three-way confining pressure loading
drilling, and designing a reasonable test plan;
[0057] step 2) preparing the corresponding test piece according to
the test solution;
[0058] step 3) performing a three-way confining pressure drilling
test on the prepared test piece, collecting the drilling parameters
in a drilling process of the test piece during the test, and
collecting the rock core of the test piece;
[0059] according to different test purposes, step 4) is performed
in two ways:
[0060] step 4a) performing statistics on the core collection rate
of the rock core of the test piece, and measuring the integrity
parameter RQD value of the test piece;
[0061] step 4b) cutting and grinding the rock core obtained from
the test piece to prepare a plurality of standard test pieces, and
performing a triaxial test and a uniaxial test to measure the
mechanical property parameters of the test piece material;
[0062] step 5) preprocessing the collected data, and then
establishing the relationship between the processed data and the
same-depth rock mechanical properties and rock mass integrity
parameters.
[0063] Further, the drilling parameters include a drilling rate, a
torque, a rotating speed, a drilling pressure and derived drilling
specific work; the mechanical property parameters of the rock mass
include uniaxial compressive strength, the Poisson's ratio, an
internal friction angle, and modulus of elasticity; and the rock
mass integrity parameter is represented by an RQD value.
[0064] The test purpose in the step 1) includes: A. establishing
the relationship between the drilling parameters of the test piece
and the mechanical properties of the rock mass under different
confining pressures, and B. establishing the relationship between
the rock mass integrity parameter RQD value and the drilling
parameters;
[0065] the rock mass basic factors affecting the three-way
confining pressure loading drilling in the step 1), for the purpose
A, the basic factors are rock mass types, including granites,
marbles, sandstones, shale and other rock masses of different types
and from different origins; and for the purpose B, the basic
factors are a rock fissure development degree and a fracture
condition.
[0066] In the step 2), the relationship between the drilling
parameters of the test piece and the mechanical properties of the
rock mass under different confining pressures is tested, and the
test piece can be a complete rock mass test piece or a fractured
rock mass test piece;
[0067] the complete rock mass test piece is obtained by cutting and
grinding different types of natural rocks according to the size
requirements of the test piece of the multifunctional true triaxial
rock drilling test system;
[0068] the complete rock mass test piece refers to a concrete or
mortar test piece with different strength according to the size
requirements of the test piece of the multifunctional true triaxial
rock drilling test system;
[0069] the fractured rock mass test piece is obtained by
respectively burying polyethylene pieces with different angles,
different thicknesses and different distances in similar materials
of the rock mass in advance according to the requirements of
fracture parameters of the rock mass in the test solution, taking
out the polyethylene pieces from the similar materials after
primary solidification, demolding after the test piece is
solidified and curing the test piece in a specific environment.
[0070] In the step 1), in view of the test of establishing the
relationship between the rock mass integrity parameter RQD value
and the drilling parameters, the test piece used is the fractured
rock mass test piece, rock with a cross section of 300.times.300 mm
and horizontal and smooth upper and lower surfaces and a sand or
gravel layer are alternately placed in the pressure chamber and are
circulated in several layers, and the height of each layer of rock
and the sand or gravel layer can be varied according to the design
of the test solution.
[0071] In the step 3), the rock core has a rock core diameter of 50
mm, after the drilling test is completed, the test piece is taken
out, and then 3-4 drilling holes are drilled in the periphery of a
test hole of the drilling rig, and the drilling hole serial number
is k (k=1, 2, 3 . . . ).
[0072] In the step 4a), performing statistics on the core
collection rate of the rock core of the test piece, and measuring
the RQD value of the test piece includes: firstly performing
statistics on the RQD value of each drilling hole, and then using
the average value of the RQD value of each drilling hole as the RQD
value of the test piece, and the RQD value of each drilling hole is
the percentage of the ratio of the cumulative length of the rock
core greater than 10 cm in the rock cores taken from each drilling
hole to the drilling length of the drilling hole.
[0073] In the step 4b), the measurement of the mechanical property
parameters of the test piece materials includes: cutting the rock
core of each drilling hole into a standard test piece having a
height of 100 mm, the standard test piece at the upper part to the
test piece at the bottom end are sequentially marked as i, the
depth of the ith standard test piece of the kth hole in the test
piece is 100 (i-1) to 100i mm, and the standard test pieces having
the same mark are grouped, for example, the ith standard test
pieces of all holes belong to the ith group, and the uniaxial test
and the triaxial test are performed on the ith group of standard
test pieces to obtain the mechanical property parameters (uniaxial
compressive strength R.sub.c, cohesive force c, internal friction
angle .psi., modulus of elasticity E) of the ith group to serve as
the mechanical property parameters of test pieces at the depth of
100 (i-1) to 100i mm.
[0074] In the step 5), in view of the test of establishing the
relationship between the rock mass integrity parameter RQD value
and the drilling parameters, the collected data is preprocessed,
the rotating speed r' and the torque m' sensitive to the fracture
degree of the rock mass are processed to obtain a torque
significant rate i and a rotating speed significant rate r.
[0075] The torque significant rate m and a rotating speed
significant rate r are as follows:
m.sub.k=|m.sub.k'-m.sub.k+1'|/m.sub.k'
r.sub.k=|r.sub.k'-r.sub.k+1'|/r.sub.k'
in which k represents the kth collection point of the data.
[0076] The critical value of the torque significant rate and the
critical value of the rotating speed significant rate are obtained
according to the test by using the same determination method, and
the determination of the critical value of the torque significant
rate is taken as an example. The critical value of the torque
significant rate is determined according to the following method:
recording a torque value when the fracture is encountered during
the drilling process, calculating the torque significant rate m,
using all torque significant rates m when the fracture occurs in
the drilling process as sample data, using the torque significant
rates m corresponding to a confidence probability of 95% as a
truncation probability of the sample parameters of the torque
significant rate m according to a normal probability distribution
model of the sample data, and determining the critical value of the
torque significant rate.
[0077] In the step 5), in view of the test of establishing the
relationship between the rock mass integrity parameter RQD value
and the drilling parameters, establishing the relationship between
the processed data and the rock mass integrity parameter RQD
includes: on the basis of a large number of test data, performing
formula fitting on the RQD value of the test piece, a torque
fracture index QD.sub.m and a rotating speed fracture index
QD.sub.r by using a multiple linear regression method, and the
final form of the fitting formula is:
RQD=.beta..sub.0+.beta..sub.1QD.sub.m+.beta..sub.2QD.sub.r
in which .beta..sub.0, .beta..sub.1 and .beta..sub.2 all represent
regression coefficients.
[0078] The torque fracture index QD.sub.m and a rotating speed
fracture index QD.sub.r are as follows:
QD m = h i 1 + l j 1 H ##EQU00001## QD r = h i 2 + l j 2 H
##EQU00001.2##
[0079] In the formula, h.sub.i.sup.1 represents the length of the
ith segment of which the torque significant rate m is less than the
critical value in a certain drilling hole, and l.sub.i.sup.1l.sub.j
represents the length of the jth segment of which the torque
significant rate index is greater than the critical value and the
length is less than 100 mm. h.sub.i.sup.2 represents the length of
the ith segment in which the rotating speed significant rate m is
greater than the critical value, l.sub.i.sup.2 represents the
length of the jth segment of which the rotating speed significant
rate index is greater than the critical value and the length is
less than 100 mm, and H represents the total length of a certain
drilling hole.
[0080] In the step 5), in view of the test of establishing the
relationship between the drilling parameters of the test piece and
the mechanical properties of the rock mass under different
confining pressures, preprocessing the collected data refers to
segmenting the collected drilling rate v', the torque m', the
rotating speed r', the drilling pressure n' of the test piece and
the deduced drilling specific work w' data from the top to the
bottom of the test piece at an interval of 100 mm, the ith segment
represents that the depth of the test piece is 100 (i-1) to 100i
mm, and an arithmetic mean value of the indexes of the segment is
used as a representative value of the segment (the drilling rate v,
the torque m, the rotating speed r, the drilling pressure n, and
the deduced drilling specific work w).
[0081] In the step 5), establishing the relationship between the
processed data and the same-depth rock mechanical properties
includes: respectively performing regression on an optimal
relational expression between the representative values of the
drilling parameters and the mechanical property parameters of the
rock in a stepwise regression method, including: fitting the
optimal relational expression between the uniaxial compressive
strength R.sub.c and the representative values of the drilling
parameters, fitting the optimal relational expression between the
cohesive force c and the representative values of the drilling
parameters, fitting the optimal relational expression between the
internal friction angle .psi. and the representative values of the
drilling parameters, and fitting the optimal relational expression
between the modulus of elasticity E and the representative values
of the drilling parameters. The fitting methods and operation steps
of the four relational expressions are the same, and are
illustrated by taking the fitting of the optimal relational
expression between the internal friction angle .psi. and the
representative values of the drilling parameters as an example, and
the following several steps are contained:
[0082] (1) defining independent variables and dependent variables,
and calculating a correlation coefficient matrix, which includes 4
sub-steps.
[0083] A. the independent variables are the torque x.sub.1, the
rotating speed x.sub.2, the drilling pressure x.sub.3, the drilling
rate x.sub.4, and the drilling specific work x.sub.5, the dependent
variable is the internal friction angle y.sub.1, and a 5-variable
regression model is:
=b.sub.0+b.sub.1x.sub.1+b.sub.2x.sub.2+b.sub.3x.sub.3+b.sub.4x.sub.4+b.s-
ub.5x.sub.5
[0084] B. Calculating the Average Value of the Variables
[0085] For the independent variables and the dependent variables,
there are n groups of data according to a large number of field
tests, and then the average number of variables is:
x i _ = 1 n 1 n x ki ##EQU00002## y _ = 1 n 1 n y k
##EQU00002.2##
[0086] X.sub.ki represents the value of x.sub.i in the kth test
data.
[0087] C. Calculating a Deviation Matrix
[0088] The sum of squares of the independent variables is SS.sub.i,
and the sum of products of the independent variables and the
dependent variables are SP.sub.ij and SP.sub.iy
SS i = 1 n ( x ki - x i _ ) 2 ##EQU00003## SP ij = 1 n ( x ki - x i
_ ) ( x kj - x j _ ) ##EQU00003.2## SP iy = 1 n ( x ki - x i _ ) (
y k - y _ ) ##EQU00003.3##
then a normal equation is obtained
{ SS 1 b 1 + SP 12 b 2 + SP 13 b 3 + S 14 b 4 + SP 15 b 5 = SP 1 y
SS 51 b 1 + SP 52 b 2 + SP 53 b 3 + SP 54 b 4 + SP 55 b 5 = SP 5 y
##EQU00004##
[0089] D. Calculating a Correlation Coefficient Matrix
[0090] In the stepwise regression, for ease of expression and
calculation, the dispersion is usually transformed into a
correlation matrix, and the calculation formula is:
r.sub.iy=SP.sub.ij/(SS.sub.iSS.sub.j).sup.0.5
in which, i,j=1, 2, 3, 4, 5, r.sub.iy represents the correlation
coefficient of x1, x2, x3, x4, x5 and y; and the correlation
coefficient matrix is:
{ r 11 p 1 + r 12 p 2 + r 13 p 3 + r 14 p 4 + r 15 p 5 = r 1 y r 51
p 1 + r 52 p 2 + r 53 p 3 + r 54 p 4 + r 55 p 5 = r 5 y
##EQU00005##
then the correlation coefficient matrix is:
R.sup.(0)=[r.sub.ij.sup.(0)]
In the formula, 0 represents the original correlation
coefficient.
[0091] (2) Determining the F Test Standard of the Significance
[0092] The observation number n of the test sample is much greater
than the number m of the independent variables, then the influence
of the number m of the independent variables introduced on the
degree of freedom of the remaining independent variables is small.
At this time, a fixed F test value is selected without being
replaced, the level of significance .alpha. should not be too
small, for example, .alpha.=0.1. F.sub..alpha. represents the F
value when the level of significance is a, which can be obtained by
searching for a test critical value table of F.
[0093] (3) Selecting the First Independent Variable
[0094] A. Calculating a Partial Regression Square Sum u.sub.i of 5
Independent Variables
u.sub.i=r.sub.iy.sup.2/r.sub.ii(i=1,2,3,4,5)
[0095] A greater u.sub.i value indicates greater contribution of
the independent variable to the variance after the independent
variable is introduced into the regression equation, the
independent variable is introduced into the regression equation at
first, for example, x.sub.k is introduced into the regression
equation.
[0096] B. After the independent variable x.sub.k is introduced, the
correlation coefficient matrix R.sup.(l) is changed by the
following formula and is transformed into R.sup.(l+1).
{ r kk ( l + 1 ) = 1 / r kk ( l ) r kj ( l + 1 ) = r kj ( l ) / r
kk ( l ) ( j .noteq. k ) r ik ( l + 1 ) = - r ik ( l ) / r kk ( l )
( i .noteq. k ) r ij ( l + 1 ) = r ij ( l ) - r ik ( l ) r kj ( l )
/ r kk ( l ) ( i , j .noteq. k ) ##EQU00006##
[0097] (4) Selecting the Second Independent Variable
[0098] A. Calculating the Regression Square Sum of the Independent
Variables
u.sub.i.sup.(2)=[r.sub.iy.sup.(1)].sup.2/r.sub.ii.sup.(1)(i=1,2,3,4,5)
[0099] Excluding the introduced x.sub.k, the maximum independent
variable in the independent variable u.sub.i.sup.(2)u.sub.i.sup.(2)
is introduced into the regression equation, for example,
x.sub.l.
[0100] B. performing F test on the introduced independent variable
x.sub.l.
F.sub.l=u.sub.5.sup.(2)/[(1-u.sub.k.sup.(1)-u.sub.l.sup.(2))/(n-2-1)]
[0101] If F.sub.l>F.sub..alpha.F.sub.l>F.sub..alpha., then
x.sub.l is introduced, otherwise, x.sub.l is not introduced.
[0102] C. After x.sub.l is introduced, performing variation
according to the formula R.sup.(l+1), and transforming R.sup.(1)
into R.sup.(2).
[0103] D. performing a significance test on the introduced x.sub.k
and x.sub.l
[0104] First, the partial regression square sum and the remaining
square sum are calculated.
u.sub.i.sup.(3)=[r.sub.iy.sup.(2)].sup.2/r.sub.ii.sup.(2)(i=1,2,3,4,5)
[0105] If
u.sub.k.sup.(3)>u.sub.i.sup.3u.sub.k.sup.(3)>u.sub.l.sup.(-
3), x.sub.k and x.sub.l are significant and retained, or otherwise,
x.sub.k is eliminated.
[0106] (5) Repeating the step (4) until all independent variables
are extracted
[0107] (6) Establishing an optimal regression equation
[0108] In the stepwise regression analysis, the standardized
quantity is used, that is, the solution p.sub.i obtained from the
correlation coefficient is a standard regression coefficient, and
then the standard regression coefficient is converted into a
partial regression coefficient b.sub.i,
b i = p i S y S xi ##EQU00007##
assuming that x.sub.k, x.sub.l and x.sub.z are all selected
independent variables, and b.sub.i, b.sub.k, b.sub.z are partial
regression coefficients corresponding to the independent
variables;
b.sub.0=y.sub.1-b.sub.lx.sub.l-b.sub.kx.sub.k-b.sub.zx.sub.z
[0109] The optimal regression equation is:
=b.sub.0+b.sub.kx.sub.k+b.sub.lx.sub.l+b.sub.zx.sub.z.
[0110] The drilling test in the step 3) using the true triaxial
rock drilling tester includes the following steps:
[0111] Step A: the test piece is placed on a test piece platform in
the pressure chamber composed of the lateral loading plates for
applying the confining pressure, and then the pressure chamber is
pushed into the center of a test bench.
[0112] Step B: a set confining pressure value is input to computer
software matched with the logic controller, the logic controller
controls the hydraulic pump station to work, hydraulic oil enters
the four lateral hydraulic oil cylinders and pushes the lateral
loading plates to apply a lateral pressure to the test piece, and
the lateral confining pressure sensor receives a pressure signal of
the lateral hydraulic oil cylinders at all times and dynamically
maintains the confining pressure together with the logic
controller.
[0113] Step C: a set axial pressure value is input in the software,
the axial hydraulic oil cylinder drives the axial loading plate to
lift the pressure chamber, so that the test piece contacts the
platform plate at the bottom of the top reaction force frame and
squeezes each other to generate an axial force function, and the
axial pressure sensor dynamically maintains the axial pressure
together with the logic controller.
[0114] Step D: the operating parameters of the core collection
drilling rig are set in the software, the logic controller controls
the servo motor of the hydraulic pump station and the drilling rig
servo motor, and then controls the drilling rig top hydraulic oil
cylinder to push the drilling rig unit to move downward so as to
continue drilling, the drilling rig displacement sensor and the
rotating speed sensor monitor the drilling rate and the rotating
speed in the drilling process at all times, and cooperate with the
logic controller, the servo motor and the speed reducer in the
drilling rig to make the drilling rig work under the set parameters
until the drilling is completed.
[0115] The third solution provided by the present invention is as
follows:
[0116] A method for evaluating an anchoring and grouting
reinforcement effect based on drilling parameters is provided,
including: performing an indoor drilling test on the rock test
piece obtained onsite before and after anchoring and grouting
reinforcement based on the above multifunctional true triaxial rock
drilling test system, designing an anchoring and grouting
reinforcement solution according to the representative value of the
equivalent uniaxial compressive strength of the test piece before
the anchoring and grouting reinforcement, and judging the
reasonableness of the anchoring and grouting reinforcement solution
via a guarantee rate .lamda. of the equivalent uniaxial compressive
strength after the test piece is reinforced.
[0117] A method for evaluating an anchoring and grouting
reinforcement effect based on drilling parameters includes the
following specific steps:
[0118] Step A): taking onsite fractured rocks in an underground
engineering, manufacturing indoor drilling test pieces, and
dividing the indoor drilling test pieces into several groups;
[0119] step B): taking any group as an example, randomly taking a
part of test pieces, implementing an indoor drilling test,
recording the drilling parameters of three test pieces,
substituting the drilling parameters of each test piece into the
optimal regression relational expression of the uniaxial
compressive strength and the drilling parameters in the step 5) in
the second solution to obtain the equivalent uniaxial compressive
strength of each test piece, and then obtaining a representative
value of the equivalent uniaxial compressive strength of the group
of fractured rock masses; step C): comparing the representative
value of the equivalent uniaxial compressive strength obtained in
the step B) with an expected strength value, designing an anchoring
and grouting solution, implementing the same anchoring and grouting
reinforcement solution on the rest test pieces in the group, and
curing the test pieces under the same conditions;
[0120] step D): performing the indoor drilling test on the cured
reinforced test piece, and substituting the drilling parameters
into the optimal regression relational expression of the uniaxial
compressive strength and the drilling parameters in the step 5) to
obtain the equivalent uniaxial compressive strength of each test
piece;
[0121] step E): calculating a guarantee rate of the equivalent
uniaxial compressive strength after the reinforcement of the group
of test pieces, if the guarantee rate is greater than 95%, judging
that the grouting reinforcement solution is reasonable, or
otherwise, judging that the grouting reinforcement solution is
unreasonable.
[0122] Further, the calculation method of the equivalent
compressive strength of the test piece in the step C) includes:
substituting the drilling parameters, including the torque m, the
rotating speed r, the drilling pressure n and the drilling specific
work w of the drilling rig into the optimal regression relational
expression of the uniaxial compressive strength and the drilling
parameters in the step 5) in the second solution to obtain the
equivalent uniaxial compressive strength of each test piece.
[0123] Further, the representative value of the equivalent uniaxial
compressive strength of the fractured rock mass is represented by
the average value of the equivalent compressive strengths of part
of test pieces; if the deviation between the maximum value and the
average value or between the minimum value and the average value is
greater than 15%, an intermediate value is used as the
representative value, and if the deviations between the maximum
value and the average value and the deviations between the minimum
value and the average value are both greater than 15%, the group of
data is invalid.
[0124] Further, the anchoring and grouting reinforcement solution
is to determine a slurry-water-cement ratio, a grouting pressure,
an anchor rod length and an anchor rod diameter.
[0125] Further, the calculation method of the guarantee rate of the
equivalent uniaxial compressive strength is:
.lamda. = num N .times. 100 % ##EQU00008##
[0126] in which num represents the number of reinforced test pieces
with equivalent uniaxial compressive strength greater than the
expected strength value in the group, and N represents the total
number of the reinforced test pieces in the group.
[0127] The beneficial effects of the present invention are as
follows:
[0128] (1) The multifunctional true triaxial rock drilling test
system provided by the present invention can impart a three-way
pressure to the test piece, and truly simulate the stress state of
the rock in the underground engineering and the drilling working
environment.
[0129] (2) The multifunctional true triaxial rock drilling test
system of the present invention also has the functions of a single
shaft and a rock mass true triaxial press machine, and can also
continuously heat the test piece by using a special steel heating
plate, further perform a research on the mechanical properties of
the test piece and the influence on the drilling parameters under
the action of thermal coupling, and perform a research on the
mechanical properties of the rock mass under the action of thermal
coupling. In addition, the water-containing rock mass can be placed
in the rubber box so that the tester can test the water-containing
rock mass, and the test system has a multifunctional feature.
[0130] (3) According to the method for evaluating the anchoring and
grouting reinforcement effect based on drilling parameters provided
by the present invention, the equivalent compressive strength index
is introduced to avoid the problem that the mechanical parameters
of the fractured rock mass cannot be tested before the anchoring
and grouting reinforcement to result in that the anchoring and
grouting reinforcement effect cannot be quantitatively
evaluated.
[0131] (4) According to the method for evaluating the anchoring and
grouting reinforcement effect based on drilling parameters provided
by the present invention, rapid quantitative evaluation is
performed on the anchoring and grouting reinforcement effect to
quickly judge the rationality of the anchoring and grouting
reinforcement effect so as to adjust the anchoring and grouting
solution in time, therefore the method has realistic scientific
research and engineering significance.
[0132] (5) By adoption of the multifunctional true triaxial rock
drilling tester and the test method proposed by the present
invention, the drilling parameters, the mechanical properties of
the rock mass and the fracture boundary conditions are established
to replace the step of onsite core collection for indoor test,
thereby not only reducing the time from the onsite core collection
to the acquisition of a test report, but also avoiding the problem
that the collected rock core has been removed from the original
environmental stress, temperature and other constraint conditions,
such that the rock core cannot well represent the strength of the
rock mass, and the problem that the rock core collection rate and
integrity are difficult to guarantee during drilling in weak and
fractured complex stratum so that the physical properties and
mechanical parameters of the local rock stratum cannot be obtained
is solved, and then, the measured surrounding rock strength is more
scientific and reliable.
[0133] (6) The drilling test system provided by the present
invention can measure the displacement, the drilling rate, the
rotating speed and torque parameters in the drilling process of the
drilling rig, and can set the drilling rate and the rotating speed
or set the drilling rate and the torque to achieve constant
displacement drilling, and can also set the drilling pressure and
the rotating speed or set the drilling pressure and the torque to
achieve constant pressure drilling.
BRIEF DESCRIPTION OF THE DRAWINGS
[0134] FIG. 1 is a schematic diagram of a front structure of a
multifunctional true triaxial rock drilling test system according
to the present invention.
[0135] FIG. 2 is a schematic diagram of a side structure of the
multifunctional true triaxial rock drilling test system according
to the present invention.
[0136] FIG. 3 is a schematic diagram of sections of a confining
pressure application device and a pressure chamber in the device
according to the present invention.
[0137] FIG. 4 is a schematic block diagram of a monitoring control
system in the device according to the present invention.
[0138] FIG. 5 is a structural schematic diagram of a heating plate
in the device according to the present invention.
REFERENCE SIGNS
[0139] 1, main frame upper upright post; 2, top reaction force
frame; 3, platform plate; 4, main frame lower upright post; 5,
pressure chamber; 6, test piece; 7, lateral loading plate; 8,
positioning ball; 9, wheel; 10, axial loading plate; 11, axial
hydraulic oil cylinder; 12, inner piston rod of axial hydraulic oil
cylinder; 13, main frame bottom platform; 14, guide rail base; 15,
drilling rig fixing plate; 16, drilling rig servo motor; 17, speed
reducer; 18, belt transmission device; 19, drill pipe; 20, torque
sensor, 21, lateral hydraulic oil cylinder, 22, lateral piston rod;
23, test piece cushion block; 24, pressure chamber rail; 25,
drilling rig top hydraulic oil cylinder; 26, lateral reaction force
plate; 27, lateral rib of pressure chamber, 28, bottom plate of
pressure chamber; 29, logic controller; 30 heating plate; 31,
pipeline inlet; 32, pipeline; 33, pipeline outlet.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0140] The technical solutions in the embodiments of the present
invention will be clearly and completely described below with
reference to the drawings.
[0141] As shown in FIG. 1 and FIG. 2, a multifunctional true
triaxial rock drilling test system includes a supporting frame with
a reaction force frame at the top, a pressure chamber is arranged
in the supporting frame, a test piece platform for placing a test
piece is arranged in the pressure chamber, a surrounding rock
loading device is arranged on the side of the pressure chamber, an
axial pressure loading device for contact between the upper part of
the test piece and the reaction force frame is arranged at the
bottom of the pressure chamber, a drilling rig unit capable of
lifting and rotating is arranged at the upper part of the reaction
force frame, and the drilling tester further includes a sensor for
measuring drilling parameters of the test piece, and a monitoring
control system connected with the sensor.
[0142] The sensor includes an axial displacement sensor arranged at
the bottom of the test piece platform, a drilling rig rotating
speed sensor and a drilling rig torque sensor arranged on the
drilling rig, and a lateral confining pressure sensor and a lateral
displacement sensor arranged on the surrounding rock loading
device.
[0143] The bottom of the supporting frame is supported on the test
bench or on the ground. A cylindrical concave hole is formed in the
middle of a main frame bottom platform 13, an axial hydraulic oil
cylinder 11 is placed in the concave hole, a piston rod protrudes
from the top of the axial hydraulic oil cylinder, the piston rod is
fixedly connected to an axial loading plate 10, the piston rod and
the test bench are sealed by a sealing plug, a test piece 6 is
placed on the test piece platform, a top reaction force frame 2 is
arranged at the top of the test piece 6, and the top reaction force
frame 2 is supported by a main frame upper upright post 1 and a
main frame lower upright post 4.
[0144] The working principle of the axial loading device is as
follows: a hydraulic pump pushes hydraulic oil into the axial
hydraulic oil cylinder 11 to push the piston rod 12 in the axial
hydraulic oil cylinder to move upward, and after moving upward for
a distance, the axial loading plate 10 pushes the test piece 6 to
move upward and contact the top reaction force frame 2 to apply a
force. The piston rod is a variable-section piston rod having a
circular cross section at the bottom, and the cross section of the
circular piston rod is increased for several times from bottom to
top, and the top of the piston rod is fixedly connected with a
square steel axial loading plate 10.
[0145] The bottom of the pressure chamber is spaced apart from a
pressure chamber rail 24 with a set distance, and the axial loading
plate 10 is arranged at the upper part of the rail, and the
pressure chamber is slidable on the rail.
[0146] A platform plate 3 is fixedly connected to the lower part of
the top reaction force frame, and is directly in contact with the
test piece 6, and reserved holes are formed in the middles of the
platform plate 3 and the reaction force frame to allow passage of
the drill pipe of the drilling rig.
[0147] With respect to the confining pressure loading device, the
test piece 6 is provided with a lateral hydraulic oil cylinder 21
on each side face, the lateral hydraulic oil cylinder 21 extends
out from a lateral piston rod, the lateral piston rod 22 is fixedly
connected to a lateral loading plate 7, the end part of the lateral
hydraulic oil cylinder is embedded in a lateral reaction force
plate 26 to provide a supporting reaction force for the lateral
hydraulic oil cylinder 21, and a lateral rib 27 of the pressure
chamber is arranged on one side of the lateral reaction force plate
26, the confining pressure loading device is placed on the test
piece platform, can move up and down with the test piece platform
and is pulled out along the rail, the lateral hydraulic oil
cylinder adjacent to the confining pressure loading device can be
independently controlled, that is, unequal pressures can be applied
to the side faces of the adjacent test pieces 6.
[0148] The lateral loading plate 7 is a rectangular steel plate,
which applies a horizontal pressure to the test piece under the
push of the piston driven by the hydraulic oil cylinder, the height
of the loading plate is the same as that of the test piece 6, and
the width is slightly smaller than that of the test piece 6 to
prevent mutual interference of the adjacent lateral loading plates
7 after the test piece is compressed and deformed.
[0149] A drilling rig slide rail is a drilling rig top hydraulic
oil cylinder 25 arranged at the top of the reaction force frame
through a drilling rig fixing plate 15, the drilling rig can move
up and down along the drilling rig slide rail, the drilling rig is
fixedly connected with a drilling rig servo motor 16 and move
upward or downward under the push or pull of the piston at the top
of the drilling rig in the hydraulic oil cylinder of the upper
drilling rig, the drilling rig servo motor 16 provides a rotating
force for the drilling rig, the drilling rig top hydraulic oil
cylinder 25 provides a downward pressure for the drilling rig, the
drill pipe of a drilling bit of the drilling rig is in contact with
the test piece through the reserved holes of the reaction force
frame 2 at the top of the test piece and the loading plate for
drilling, the main shaft of the drilling rig servo motor 16 is
inserted into a speed reducer 17, a belt transmission device is
arranged between the main shaft and a drill pipe 19, the belt
transmission device is connected with the speed reducer at one end
through a gear, and is connected with the main shaft of the servo
motor at the other end, the belt transmission device and the speed
reducer constitute a two-stage speed reduction mechanism, and the
reduction multiples is changed with the diameter ratio of the gears
at both ends of the belt.
[0150] The drilling rig can be arranged as a rotary cutting
drilling rig or an impact drilling rig. The drilling bit of the
rotary cutting drilling rig can be arranged as a core collection
drilling bit and can also be set as a non-core collection drilling
bit.
[0151] The monitoring control system consists of an axial pressure
sensor, an axial displacement sensor, four lateral confining
pressure sensors, four lateral displacement sensors, a drilling rig
rotating speed sensor, a drilling rig torque sensor 20, a drilling
rig pressure sensor, a drilling rig displacement sensor, a logic
controller 29, a power amplifier and a servo motor.
[0152] The monitoring control system can control the axial pressure
and the confining pressure, and can also control either of two
groups of values of the drilling rig, namely the torque and the
rotating speed, and the drilling pressure and the displacement.
[0153] The working process is as follows: the logic controller
accepts signals of the respective sensors, compares the signals
with set values, and issues a voltage instruction to control the
servo motor to work via the power amplifier and realize closed loop
control.
[0154] The present invention has the function of a uniaxial test
machine. A uniaxial test piece is placed in the pressure chamber 5,
steel cushion blocks 23 are placed on and below the uniaxial test
piece, the axial loading device lifts the pressure chamber 5, so
that the steel cushion blocks 23 on the uniaxial test piece are in
contact with the platform plate 3 below the reaction force frame 2,
the uniaxial test piece is in a uniaxial compression state, the
axial load loading device is controlled to be in a constant strain
loading mode, and the axial pressure is applied to the test piece
at a loading speed suggested by the International Society for Rock
Mechanics until the test piece is broken.
[0155] The multifunctional true triaxial rock drilling test system
can perform constant pressure incremental loading by using the
axial pressure loading device and the confining pressure loading
device, can realize the independent application of three main
stresses of the rock mass test piece, and has a part of functions
of a rock mass true triaxial test machine.
[0156] In the case that the test piece contains water therein or is
filled with fracture water, the test piece can be placed in a
high-pressure sealing rubber box having an inner size being
consistent with the size of the test piece, the top of the test
piece may be covered with a rubber cover slightly larger than the
bottom rubber box, a pore is reserved in the area of the rubber
cover through which the drilling bit and the drill pipe of the
drilling rig penetrate, the axial and lateral loading plates apply
the pressure to the rubber box and the rubber cover, and a
three-way pressure is applied to the test piece through the rubber
box and the rubber cover. This design can prevent the internal
water from flowing outside, so that the tester can test the
water-containing rock mass.
[0157] At the outside of the test piece 6, as shown in FIG. 5, a
special steel heating plate 30 is placed on the inner side of the
lateral loading plate 7, the thickness of the heating plate 30 is
greater than 20 mm, a curved pipeline 32 is arranged in the heating
plate 30, a pipeline inlet 31 is welded on one side face of the top
heating plate, a pipeline outlet 33 is welded on the lower end of
an opposite side face, so that water vapor or high temperature
liquid passes through the pipeline to heat the test piece, and then
the mechanical properties of the test piece under thermal coupling
are studied.
Embodiment 1
[0158] In the device of the embodiment, it is taken as an example
that the drilling bit used in a drilling rig module is a core
collection drilling bit, and in addition, a non-core collection
drilling bit can also be selected.
[0159] First step: the test piece 6 is manufactured, the pressure
chamber 5 is pulled out to the end part of a guide rail base 14
along the pressure chamber rail 24, the test piece 6 is placed at
the central position of the pressure chamber 5, and then the
pressure chamber 5 is pushed into the other end of the pressure
chamber rail 24.
[0160] Second step: a set axial pressure value is input in a
control module, the logic controller controls the servo motor of a
hydraulic station to drive the hydraulic pump to provide power for
the axial hydraulic oil cylinder 11, the axial loading plate 10
moves up and down under the push of the piston rod 12 of the axial
hydraulic oil cylinder, so that a positioning ball 8 ascends to
enter a positioning hole reserved in the center of a bottom plate
28 of the pressure chamber to complete the positioning work, the
axial loading plate 10 lifts the pressure chamber 5, so that the
test piece 6 or the cushion block 23 at the upper part of the test
piece contact with the platform plate 3 at the bottom of the main
frame reaction force frame 2 to press against each other to
generate an axial force, and the axial pressure sensor receives
pressure signals of the axial hydraulic oil cylinder 11 at all
times, transmits the pressure signals to the logic controller 29,
and compares the pressure signals with a set value to dynamically
maintain the axial pressure.
[0161] Third step: a set confining pressure value is input in the
control module, the logic controller 29 controls the servo motor of
the hydraulic station to drive the hydraulic pump to provide force
for the lateral hydraulic oil cylinder 21, thereby pushing the
lateral loading plate 7 to pressurize the side of the test piece 6,
and the lateral confining pressure sensor receives the pressure
signals of the lateral hydraulic oil cylinder 21 at all times,
transmits the pressure signals to the logic controller 29, and
compares the pressure signals with the set value to dynamically
maintain the confining pressure.
[0162] Fourth step: operating parameters of the drilling rig unit,
such as the drilling rate and the rotating speed of the drilling
rig, are set in the software, and the logic controller 29 controls
the drilling rig servo motor 16 to rotate the drilling rig at a
preset rotating speed, the logic controller 29 controls the servo
motor of the hydraulic pump station to provide hydraulic power for
the drilling rig top hydraulic oil cylinder 25, so as to push the
drilling rig unit to move downward, the drilling bit and the drill
pipe penetrate through the reserved holes in the main frame
reaction force frame 2 and the platform plate 3 at the top of the
test piece to contact the test piece 6 for continuous drilling, the
drilling rig displacement sensor and the rotating speed sensor
constantly monitor the drilling rate and the rotating speed in the
drilling process of the drilling rig and transmit the drilling rate
and the rotating speed to the control module so as to dynamically
maintain a constant drilling rate and rotating speed, and the
drilling rig torque and the drilling pressure of the drilling rig
are measured and are recorded in the logic controller until the
test piece is drilled through.
[0163] Fifth step: after the fourth step is completed, the rock
core is taken out from the core collection drill pipe, and is cut
and polished to manufacture a standard rock test piece.
[0164] Sixth step: the confining pressure of the test piece 6 is
released, the pressure chamber 5 is lowered onto the pressure
chamber rail 24, the pressure chamber 5 is pulled out to the end
part of the guide rail base 14 along the pressure chamber rail 24,
the standard rock test piece obtained in the fifth step and the
corresponding cushion blocks are placed at the center of the
pressure chamber 5, and then the pressure chamber 5 is pushed into
the other end of the pressure chamber rail 24.
[0165] Seventh step: the constant pressure incremental loading of
the axial loading device is set by the control module, so that the
pressure increases of the hydraulic oil cylinders within a unit
time are the same, the axial loading plate 10 lifts the pressure
chamber 5, the cushion block at the upper part of the standard rock
test piece contacts the platform plates 3 at the bottom of the main
frame reaction force frame 2 to press against each other to
generate the axial force, the axial force is increased according to
a uniaxial test pressure increment value recommended by the
International Society for Rock Mechanics, the strain value and the
pressure value during the loading process are monitored until the
test piece is broken, and then the uniaxial compression test is
completed.
[0166] Eighth step: a core is taken from the rock in the same batch
as the test piece 6, the standard rock test piece is manufactured,
and an indoor triaxial compression test is executed to obtain the
modulus of elasticity, the cohesive force and the internal friction
angle of this batch of rock samples.
[0167] Ninth step: correlation analysis is performed on the torque
and pressure data of the drilling rig module of the test piece 6
measured in the drilling process and the uniaxial compressive
strength, the modulus of elasticity, the cohesive force and the
internal friction angle of the standard test piece to obtain the
relationship between the drilling parameters and mechanical
parameters (uniaxial compressive strength, modulus of elasticity,
internal friction angle, cohesive force) of different rock masses
under the three-way confining pressure.
[0168] The following control modes can be achieved in the entire
process:
[0169] The drilling rig is controlled in four modes:
[0170] A. controlling a torque and a drilling rate, and collecting
a drilling pressure and a rotating speed;
[0171] B. controlling the torque and the drilling pressure, and
collecting a rotating speed and a drilling rate;
[0172] C. controlling the rotating speed and the drilling rate, and
collecting the torque and the drilling pressure;
[0173] D. controlling the rotating speed and the drilling pressure,
and collecting the torque and the drilling rate.
[0174] The axial pressure and the confining pressure of the test
piece are controlled in three modes:
[0175] A. a constant strain loading mode, in which small strains
occurring in the test piece within a unit time are the same;
[0176] B. a constant pressure incremental loading mode, in which
the pressure increase of the hydraulic oil cylinder within the unit
time is the same;
[0177] C. a constant force maintenance mode, in which the test
piece is kept at a set confining pressure value.
Embodiment 2
[0178] A test method for characterizing rock mass characteristics
by using drilling parameters in underground engineering is
provided. The test purpose of establishing the relationship between
drilling parameters of a test piece under different confining
pressures and the mechanical properties of the rock mass is taken
an example, the specific steps are as follows:
[0179] Step 1) according to the test purpose, rock mass basic
factors affecting the three-way confining pressure loading drilling
are determined, that is, different types of rock mass tests are
prepared, such as granite, marble, limestone, transparent similar
materials, concrete blocks with different strength and other rock
types.
[0180] Step 2) a corresponding test piece is prepared according to
the test solution, and the different types of rock masses are cut
into rectangles with cross sections of 300.times.300 mm and height
of 300-600 mm.
[0181] Step 3) a three-way confining pressure drilling test is
performed on the prepared test piece, the drilling parameters in
the drilling process of the test piece are collected during the
test, and the rock core of the test piece is obtained, wherein the
specific operation steps of the three-way confining pressure
drilling test are shown in the embodiment 1.
[0182] Step 4), after the drilling test is completed, 3-4 drilling
holes are drilled in the periphery of a test hole by using a core
collection drilling rig, and the drilling hole serial number is k
(k=1, 2, 3 . . . ), the rock core of each drilling hole is cut into
a standard test piece having a height of 100 mm, the standard test
piece at the upper part to the standard test piece at the bottom
end are sequentially marked as i, the depth of the ith standard
test piece of the kth hole in the test piece is 100 (i-1) to 100i
mm, and the standard test pieces having the same mark are grouped,
for example, the ith standard test piece of all holes belongs to
the ith group, and the uniaxial test and the triaxial test are
performed on the ith group of standard test piece to obtain the
mechanical property parameters (uniaxial compressive strength
R.sub.c, cohesive force c, internal friction angle .psi., modulus
of elasticity E) of the ith group to serve as the mechanical
property parameters of test pieces at the depth of 100 (i-1) to
100i mm.
[0183] Step 5), the collected data is preprocessed, that is, the
collected drilling rate v', the torque m', the rotating speed r',
the drilling pressure n' of the test piece and the deduced drilling
specific work w' data from the top to the bottom of the test piece
at an interval of 100 mm, the ith segment represents that the depth
of the test piece is 100 (i-1) to 100i mm, and an arithmetic mean
value of the indexes of the segment is used as a representative
value of the segment (the drilling rate v, the torque m, the
rotating speed r, the drilling pressure n, and the deduced drilling
specific work w).
[0184] Step 6, regression is respectively performed on an optimal
relational expression between the representative values of the
drilling parameters and the mechanical property parameters of the
rock in a stepwise regression method, including: fitting the
optimal relational expression between the uniaxial compressive
strength R.sub.c and the representative values of the drilling
parameters, fitting the optimal relational expression between the
cohesive force c and the representative values of the drilling
parameters, fitting the optimal relational expression between the
internal friction angle .psi. and the representative values of the
drilling parameters, and fitting the optimal relational expression
between the modulus of elasticity E and the representative values
of the drilling parameters. The fitting methods and operation steps
of the four relational expressions are the same, and are
illustrated by taking the fitting of the optimal relational
expression between the internal friction angle .psi. and the
representative values of the drilling parameters as an example, and
the following several steps are contained:
[0185] (1) defining independent variables and dependent variables,
and calculating a correlation coefficient matrix, which includes 4
steps.
[0186] A. the independent variables are the torque x.sub.1, the
rotating speed x.sub.2, the drilling pressure x.sub.3, the drilling
rate x.sub.4, and the drilling specific work x.sub.5, the dependent
variable is the internal friction angle y.sub.1, and a 5-variable
regression model is:
=b.sub.0+b.sub.1x.sub.1+b.sub.2x.sub.2+b.sub.3x.sub.3+b.sub.4x.sub.4+b.s-
ub.5x.sub.5
[0187] B. Calculating the Average Value of the Variables
[0188] For the independent variables and the dependent variables,
there are n groups of data according to a large number of field
tests, and then the average number of variables is:
x i _ = 1 n 1 n x ki ##EQU00009## y _ = 1 n l n y k
##EQU00009.2##
[0189] X.sub.ki represents the value of x.sub.i in the kth test
data.
[0190] C. Calculating a Deviation Matrix
[0191] The sum of squares of the independent variables is SS.sub.i,
and the sum of products of the independent variables and the
dependent variables are SP.sub.ij and SP.sub.iy
SS i = 1 n ( x ki - x i _ ) 2 ##EQU00010## SP ij = 1 n ( x ki - x i
_ ) ( x kj - x j _ ) ##EQU00010.2## SP iy = 1 n ( x ki - x i _ ) (
y k - y _ ) ##EQU00010.3##
then a normal equation is obtained
{ SS 1 b 1 + SP 12 b 2 + SP 13 b 3 + S 14 b 4 + SP 15 b 5 = SP 1 y
SS 51 b 1 + SP 52 b 2 + SP 53 b 3 + SP 54 b 4 + SP 55 b 5 = SP 5 y
##EQU00011##
[0192] D. Calculating a Correlation Coefficient Matrix
[0193] In the stepwise regression, for ease of expression and
calculation, the dispersion is usually transformed into a
correlation matrix, and the calculation formula is:
r.sub.iy=SP.sub.ij/(SS.sub.iSS.sub.i).sup.0.5
[0194] In the formula, i, j=1, 2, 3, 4, 5, r.sub.iy represents the
correlation coefficient among x.sub.1, x.sub.2, x.sub.3, x.sub.4,
x.sub.5 and y; and the correlation coefficient matrix is:
{ r 11 p 1 + r 12 p 2 + r 13 p 3 + r 14 p 4 + r 15 p 5 = r 1 y r 51
p 1 + r 52 p 2 + r 53 p 3 + r 54 p 4 + r 55 p 5 = r 5 y
##EQU00012##
[0195] then the correlation coefficient matrix is:
R.sup.(0)=[r.sub.ij.sup.(0)]
[0196] in which, 0 represents the original correlation
coefficient.
[0197] (2) Determining the F Test Standard of the Significance
[0198] The observation number n of the test sample is much greater
than the number m of the independent variables, then the influence
of the number m of the independent variables introduced on the
degree of freedom of the remaining independent variables is small.
At this time, a fixed F test value is selected without being
replaced, the level of significance .alpha. should not be too
small, for example, .alpha.=0.1. F.sub..alpha. represents the F
value when the level of significance is a, which can be obtained by
searching for a critical value table of F test.
[0199] (3) Selecting the First Independent Variable
[0200] A. calculating a partial regression square sum u.sub.i of 5
independent variables
u.sub.i=r.sub.iy.sup.2/r.sub.ii(i=1,2,3,4,5)
[0201] A greater u.sub.i value indicates greater contribution of
the independent variable to the variance after the independent
variable is introduced into the regression equation, the
independent variable is introduced into the regression equation at
first, for example, x.sub.k is introduced into the regression
equation.
[0202] B. After the independent variable x.sub.k is introduced, the
correlation coefficient matrix R.sup.(l) is changed by the
following formula and is transformed into R.sup.(i+1).
{ r kk ( l + 1 ) = 1 / r kk ( l ) r kj ( l + 1 ) = r kj ( l ) / r
kk ( l ) ( j .noteq. k ) r ik ( l + 1 ) = - r ik ( l ) / r kk ( l )
( i .noteq. k ) r ij ( l + 1 ) = r ij ( l ) - r ik ( l ) r kj ( l )
/ r kk ( l ) ( i , j .noteq. k ) ##EQU00013##
[0203] (4) Selecting the Second Independent Variable
[0204] A. Calculating the Regression Square Sum of the Independent
Variables
u.sub.i.sup.(2)=[r.sub.iy.sup.(1)].sup.2/r.sub.ii.sup.(1)(i=1,2,3,4,5)
Excluding the introduced x.sub.k, the maximum independent variable
in the independent variable u.sub.i.sup.(2)u.sub.i.sup.(2) is
introduced into the regression equation, for example, x.sub.l.
[0205] B. Performing F Test on the Introduced Independent Variable
x.sub.l.
F.sub.i=u.sub.5.sup.(2)/[(1-u.sub.k.sup.(1)-u.sub.l.sup.(2))/(n-2-1)]
[0206] If F.sub.i>F.sub..alpha.F.sub.l>F.sub..alpha., then
the x.sub.l is introduced, otherwise, x.sub.l is not
introduced.
[0207] C. After x.sub.l is introduced, performing variation
according to the formula R.sup.(l+1), and transforming R.sup.(1)
into R.sup.(2).
[0208] D. Performing a Significance Test on the Introduced x.sub.k
and x.sub.l
[0209] firstly the partial regression square sum and the remaining
square sum are calculated
u.sub.i.sup.(3)=[r.sub.iy.sup.(2)].sup.2/r.sub.ii.sup.(2)(i=1,2,3,4,5)
[0210] If
u.sub.k.sup.(3)>u.sub.l.sup.3u.sub.k.sup.(3)>u.sub.l.sup.(-
3), x.sub.k and x.sub.l are significant and retained, or otherwise,
x.sub.k is eliminated.
[0211] (5) Repeating the step (4) until all independent variables
are extracted
[0212] (6) Establishing an optimal regression equation
[0213] In the stepwise regression analysis, the standardized
quantity is used, that is, the solution p.sub.i obtained from the
correlation coefficient is a standard regression coefficient, and
then the standard regression coefficient is converted into the
partial regression coefficient b.sub.i,
b i = p i S y S xi ##EQU00014##
[0214] assuming that xk, xl and xz are all selected independent
variables, and b.sub.l, b.sub.k and b.sub.z are partial regression
coefficients corresponding to the independent variables;
b.sub.0=y.sub.1-b.sub.lx.sub.l-b.sub.kx.sub.k-b.sub.zx.sub.z
[0215] The optimal regression equation is:
=b.sub.0+b.sub.kx.sub.k+b.sub.ix.sub.i+b.sub.zx.sub.z.
[0216] By means of the above calculation method, the relational
expression characterizing the rock mass characteristics can be
figured out.
[0217] The above descriptions are only a preferred embodiment of
the present invention. It should be noted that those of ordinary
skill in the art can also make several improvements and
modifications without departing from the principles of the present
invention, and these improvements and modifications should also be
regarded as the scope of protection of the present invention.
Embodiment 3
[0218] A method for evaluating an anchoring and grouting
reinforcement effect based on drilling parameters includes the
following specific steps:
[0219] Step 1: taking onsite fractured rocks in an underground
engineering, manufacturing indoor drilling test pieces, dividing
the indoor drilling test pieces into several groups and each of
which includes 15 test pieces;
[0220] step 2: taking any group as an example, randomly taking
three test pieces, implementing an indoor drilling test, recording
the drilling parameters of the three test pieces, substituting the
drilling parameters of each test piece into the optimal regression
relational expression of the uniaxial compressive strength and the
drilling parameters in the step 5) in the second solution to obtain
the equivalent uniaxial compressive strength of each test piece,
and then obtaining a representative value of the equivalent
uniaxial compressive strength of the group of the fractured rock
masses;
[0221] step 3: comparing the representative value of the equivalent
uniaxial compressive strength obtained in the step 2 with an
expected strength value, designing an anchoring and grouting
solution, implementing the same anchoring and grouting
reinforcement solution on the rest test pieces in the group,
including the slurry-water-cement ratio, the grouting pressure, the
anchor rod length and the anchor rod diameter and curing the test
pieces under the same conditions;
[0222] step 4: performing the indoor drilling test on the cured
reinforced test piece, and substituting the drilling parameters
into the optimal regression relational expression of the uniaxial
compressive strength and the drilling parameters in the step 5 of
solution 2 to obtain the equivalent uniaxial compressive strength
of each test piece;
[0223] step 5: calculating a guarantee rate of the equivalent
uniaxial compressive strength after the reinforcement of the group
of test pieces, if the guarantee rate is greater than 95%, judging
that the grouting reinforcement solution is reasonable, or
otherwise, judging that the grouting reinforcement solution is
unreasonable. The calculation formula of the guarantee rate of the
equivalent uniaxial compressive strength of the reinforced test
piece is:
.lamda. = num N .times. 100 % ##EQU00015##
[0224] In which num represents the number of reinforced test pieces
with equivalent uniaxial compressive strength greater than the
expected strength value in the group, and N represents the total
number of the reinforced test pieces in the group.
[0225] The above descriptions are only preferred embodiments of the
present invention. It should be noted that those of ordinary skill
in the art can also make several improvements and modifications
without departing from the principles of the present invention, and
these improvements and modifications should also be regarded as the
scope of protection of the present invention.
* * * * *